SUPPLEMENT 



remains, framed by the placenta or seed-bearing portion of the fruit. 

 Some of the plants of this family that children would be likely to find, 

 are enumerated in Chapter XIV of the Reader. The shepherd's 

 purse, Capsella Bursa-pastoris^ Medic., and the pepper grass, Lepi- 

 dium nitidum, Nutt., are common lawn or wayside weeds that begin 

 flowering in January. Their tiny white flowers continue to develop 

 at the end of the cluster, long after the lower part has ripened its 

 fruits. The fruits are tiny ; those of the shepherd's purse are obcor- 

 date, the others are round. The botanical name for the watercress is 

 Nasturtium officinale, Tour n.; for sweet alyssum, Lobularia (formerly 

 Alyssum) matitima, Desv., and for the wild radish that overruns 

 neglected places, Raphanus sativus, Linn. All three of these can be 

 found in bloom almost any month. The wild turnip, Brassica caui- 

 pestris^ Linn., usually known as mustard, is very common in the out- 

 skirts of civilization, blooming earlier than the black mustard ; it has 

 smooth leaves, the stem leaves clasping at the base. The field mustard, 

 or black mustard, Brassica nigra, Koch., is further treated in the 

 Reader in Chapter XVI. The lace-pod, Thysanocarpus curvipes, 

 Hook., has minute white flowers, but exceedingly pretty fruits ; the 

 fruits are not dehiscent, that is, the ovary does not open and discharge 

 the seed, but it develops a dainty, lace-like margin, called a wing, 

 which aids in seed distribution. The plant is slender, but bears many 

 long racemes of pale-green, or pinkish lace-pods ; it blooms in spring 

 time in rather sheltered places. 



The western wall-flower, Erysimum asperum, DC., is a stiff, 

 rough, hardy plant, with large, fragrant, orange-colored flowers ; it 

 begins to bloom in mid-winter, and its long racemes last for many 

 weeks. Having more handsome flowers than most Cruciferse, the 

 wall-flower can afford to be more exclusive, and its sepals cohere so 

 closely that it has practically a tube about half an inch deep. The 

 stigma is mature when the bud begins to expand, and as the expan- 

 sion is very deliberate and the honey abundant, the pollination ot any 

 flower is likely to occur before the dehiscence of its own pollen begins. 

 All Cruciferse mature stigmas before shedding pollen, and as honey is 

 usually fairly abundant and is frequently accessible to any insect, 

 there must be a considerable amount of cross pollination. So far as 

 I have observed, there has always been some provision for self pol- 

 lination later on, and insects often effect close as well as cross 

 pollination. There are many other common Cruciferae, but it would 

 be impossible to distinguish them clearly without tedious description 

 and technical terms. 



CEnothera bistotta, Nutt., is a southern species, but there are 



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